h r 7iPOW BILL OW F se e f 41 00 f r UPS y 1 r graduations on the Plastigage envelope fig 6A83 NOTE Normally main bearing journals wear evenly and are not out of round However if a bearing is being fitted to an out of round journal be sure to fit to the maximum diameter of the journal If the bearing is fitted to the minimum diameter of the journal and the journal is out of round 001 or more interference between the bearing and journal will result in rapid bearing failure If the flattened Piastigage tapers toward the middle or ends there is a difference in clearance indicating a taper low spot or other irregularity of the bearing or journal Be sure to check the journal with a micrometer if the flattened Plastigage indicates more than 001 difference NOTE Crankshaft journal diameters are 2 0978 to 2 0988 for No 1 and 2 For No 3 and 4 2 20993 20983 6 If the main bearing clearance for No 3 and No 4 main bearings is 0025 worn and 0007 to 0022 new No 1 and No 2 main bearing clearance is 004 worn and 0012 to 0027 new the bearing insert is satisfactory If the clearance is not within these limits replace the bearing insert CAUTION Do not install No 4 main bearing in No 2 or No 3 bearing locations The No 4 main bearing halves are 0015 thicker than No 2 and No 3 main bearings at the ends which are located at the lop half of the crankcase and ore thinner by the same amount at the opposite ends This has the effect of lowering the center line of the bearing 0015 The No 4 main bearing is identified by a brown dye on edges of the bearing shell NOTE Bearings are available in standard sizes and 001 002 003 010 and 020 undersize REPLACEMENT BEARINGS It clearance with Install bear plastigage Is ing sets oo1o ooo Std 0015 001 U S 0020 001 U S 0025 002 U S 0030 002 U S 0035 003 U S 0040 003 U S If these undersize bearings do not produce the proper clearance it will be necessary to regrind the crankshaft journal for use with the next undersize bearing